Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
I was too frustrated by MS and Apple for inaction on this matter. My other venerable apps like Creative Cloud that is still 32bit has had spme problems with macOS Catastrophe. So, IMHO, this is probably the biggest thing to be aware of as "important" stuff, like MS Office 2011, might not work for you on Catalina. Is there a list of software somewhere? Not sure. There might be some kind of "checker" program out there. It just forced me to uninstall Office from my Mac. Heart broke ¯\_(ツ)_/¯